1. Field of the Invention
The present invention relates to a device for properly controlling image density in an image forming equipment such as a typical copying machine.
2. Description of the Prior Art
For adjusting the density of a transfer image of a copying machine, means for changing the lighting voltage of an original exposure lamp LA1 as shown in FIG. 2 by adjusting a volume VR1 in the operation unit as shown in FIG. 1 has been employed generally. Such prior art method, however, has a drawback in that the quantity of copy sheets to be used increases more than the quantity of sheets required, since in many cases several copy sheets are wasted until an optimum image is obtained.
Alternatively, there is a method wherein original density is detected and image forming conditions, such as the quantity of charge, the quantity of exposure, and the development bias voltage, are controlled according to the detected density. Such method, however, has a drawback in that the copying time is lengthened since scanning for detecting the original density is required before the original scanning for copying.